A so-called heat pump for absorbing heat from one heat source and emitting heat to the other heat source is often used for an air conditioner or a hot water supply apparatus at the present.
In the conventional heat pump system, heat exchangers are arranged for both the heat sources, respectively, and the heat exchangers are connected to each other through a cooling medium circulating passage and generally, according to the circulation direction of the cooling medium, one of the heat exchangers is used as an evaporator and the other heat exchanger is used as a condenser to function for a freezing cycle. If one heat exchanger is arranged within a tank where a heat medium such as water is stored, according to the circulation direction of the cooling medium, warm water is stored in the tank when the heat exchanger is a condenser or cold water is stored in the tank when the heat exchanger is an evaporator.
Namely, according to the conventional technique, only warm water or cold water is contained and stored in the tank but there cannot be exerted a function of simultaneously storing both the warm and cold water in the tank.
As examples of the conventional heat pump system, there can be mentioned a system disclosed in Japanese Unexamined Patent Publication No. Sho-58-69346 and a system disclosed in Japanese Unexamined Patent Publication No. Sho-58-205040. The former apparatus is a hot water supply apparatus provided with a heat pump, in which two heat exchangers for supply of hot water are connected to each other in series. The first heat exchanger for supply of hot water is used mainly for effecting heat exchange during the condensation process of the freezing cycle and warm water of a relatively low appropriate temperature is supplied. On the other hand, the second heat exchanger for supply of hot water is used mainly for effecting heat exchange in the gas zone during the condensation process, and a part of warm water heated by the first heat exchanger is further heated to supply water of an elevated temperature.
When this hot water supply apparatus is used in households for supplying warm water of a relatively low temperature to be used for bathing, washing, face washing and cleaning and for supplying hot water of a relatively high temperature to be used as additional hot water to a bath. In this system, the disadvantage of the conventional technique in which relatively low temperature warm water is supplied by using the heat pump apparatus and an auxiliary heat source such as an electric heater is necessary for supplying hot water at a relatively high temperature is eliminated. Namely, in this heat pump apparatus, two kinds of elevated temperature water differing in the temperature are produced.
The latter apparatus has a structure in which water heat-exchanged outside is introduced into a heat accumulating tank where water is stored. When cold water is introduced into this heat accumulating tank, the heat of water taken out from the upper portion of the heat accumulating tank is discharged in the exterior heat exchanger to form cold water and this cold water is introduced into the lower portion of the heat accumulating tank, and when warm water is introduced into the heat accumulating tank, the heat of water taken out from the lower portion of the heat accumulating tank is absorbed by the exterior heat exchanger to form warm water and this warm water is introduced into the upper portion of the heat accumulating tank.
Accordingly, in this apparatus, there can be attained effects of preventing mingling of cold water and warm water in the heat accumulating tank and increasing the heat exchange efficiency of the heat exchanger. However, the heat accumulating tank of this conventional type has no function of positively producing cold water and warm water.
It is apparent from the above-description that the conventional heat pump systems have only a function of producing warm water or cold water, and a heat pump system capable of simultaneously producing two kinds of elevated temperature water differing in the temperature, two kinds of cold water differing in the temperature or cold water and warm water has not been provided.